The  Butter  mere  and  Ennerdale  Granophyre.  015 
LoweeOldRed     Red  marls  and  sandstones,  with  cornstoues  and  conglorne- 
Sandstoxe.  rates  at  the  base. 
( '  Didi/mograptits-bifidus  Beds.     Blue-black  shales,  with  one  or 
OllDOV 
ICTAN 
more  thick  bands  of  grit  towards  the  base. 
\ .  v  {  Tefragrapt us-Beds.     Black  and  buff  shales  with   thin  grit- 
bands  :  thick  bands  of  ashy  grits  and  conglomerates 
^      towards  the  base. 
These  rocks  are  described  in  detail.  They  occur  in  t,Avo  main 
anticlines,  overfolded,  and  complicated  by  thrusts  which  cut  out  a 
great  part  of  the  intervening  syncline.  They  are  covered  uncon- 
formably  hy  the  lower  beds  of  the  Old  Eed  Sandstone.  The  igneous 
rocks  occur  in  three  well-defined  areas,  which  belong  to  the  same 
petrographical  province,  near  Coomb,  at  Capel  Bethesda,  and  at 
Lambstone.  Both  inter  bedded  and  intrusive  rocks  are  represented,, 
and  full  petrographical  descriptions  of  all  types  are  given  in  the 
paper.  The  latter  include  diabases,  and  the  large  porphyry-mass 
of  Lambstone.  The  extrusive  rocks  have  been  determined  to 
occur  in  the  following  order  : — (1)  augite-andesites  ;  (2)  rhyolites  ; 
and  (3)  augite-andesites,  with  some  hornblende-andesite.  The  ex- 
trusive rocks  are  interbedded  with  fluxion-breccias  and  with  tuffs  ; 
they  are  associated  with  the  lower  members  of  the  Tetragraptus- 
Beds,  and  are  consequently  of  Lower  Arenig  age;  while  the  intrusive 
rocks  have  been  injected  into  the  extrusive  rocks,  and  have  also- 
affected  the  Tetragraptus-Beds,  but  at  what  date  exactly  it  is  im- 
possible to  say,  except  that  it  antedates  the  Old  Eed  Sandstone. 
Much  of  the  folding  and  faulting  was  accomplished  before  the  Lower 
Old  Red  Sandst  one  was  deposited,  but  certain  faults  involve  this  forma- 
tion, and  make  it  clear  that  there  was  an  important  later  movement. 
2.  'The  Buttermere  and  Ennerdale  Granophyre.'  By  Eobert 
Heron  Eastall,  B.A.,  E.G.S.  (Christ's  College,  Cambridge). 
This  paper  embodies  the  results  of  field-mapping  and  micro- 
scopical study  of  the  large  mass  of  igneous  rocks  known,  collectively, 
as  the  Buttermere  and  Ennerdale  Granophyre.  Erom  the 
facts  put  forward  it  is  concluded  that  the  intrusion  is  an  example  of 
an  acid-magma,  which  has  crystallized  under  the  peculiar  set  of  con- 
ditions that  gives  rise  to  a  very  perfect  development  of  granophyric 
structure.  These  conditions  are  probably,  to  a  certain  extent,  inter- 
mediate between  those  of  plutonic  and  true  hypabyssal  rocks.  The 
masses  appear  to  be  of  the  '  cedar-tree '  laccolite-type  intrusive 
about  the  junction  of  the  Skiddaw  Slates  and  the  Borrow  dale  rocks, 
but  penetrating  into  the  higher  rocks.  Besides  the  normal  acidic 
rock,  which  comprises  the  bulk  of  the  intrusions,  there  are  some 
marginal  patches  of  more  basic  character,  showing  obvious  genetic 
relationship,  and  slightly  earlier  in  point  of  time  than  the  intrusion 
of  the  acidic  rock.  These  basic  fore-runners  afford  evidence  of 
differentiation  of  the  magma  before  intrusion — an  example  of  Prof. 
Brogger's  deep-magmatic  differentiation.  Considered  as  a  whole, 
the  character  of  the  magma  shows  closer  affinity  to  the  tonalite- 
group  than  to  the  true  granites,  although  it  is  somewhat  more  acid 
than  the  majority  of  tonalitcs.  The  more  basic  types  include 
dolerites,  quartz-dolerites,  and  a  rock-type  intermediate  between 
